Safe Speed Forums

It never ceases to amaze me why the government, in its building regulations, does not COMPEL those building new buildings and those owners who are refurbishing the rooves of existing buildings to (re)tile their rooves with energy producing solar panels.

If a south facing roof on a typical house is covered in these tiles, the electrical energy needed from the mains (typically) is HALVED.

Rooves usually last 50 years. Even at today's prices, such a new roof would pay for iteself in perhaps 10 years. If 'everyone' were getting one, the tiles would drop through the floor, price wise.

Of course, the government would not be able to rake in as much money in tax over the livespan of all those rooves (and there would be less green house gasses - whether or not you believe in Global Warming).

So the answer is "why not"

Right now photovoltaics don't make economic sense when compared with mains electricity supplies.

A 150W photovoltaic array costs about £500 and will deliver energy for something like 8 hours a day 200 days a year. That's about 240 Kwh per year - with electricity at a maximum price of about 7p per Kwh that array generates about 17 quids worth of electricity per year. Then there's batteries, regulators, inverters, installation costs. The batteries in particular have a limited life and will require replacement at fairly regular intervals.

Then there's efficiency. One particular problem is that when the batteries are full and the energy isn't needed immediately we have no alternative but to lose it. All in all we'd be pretty lucky if we were able to use 50% of the total. - that means £8 quid's worth of electricty per year from our £500 array meaning 60 years to break even - probably more than the lifetime of the array.

I believe that material costs prevent huge benefits arising directly out of greater production volumes.

On the other hand, if mains electricity attracted duty at the same rate as motor fuel then the balance might be tipped.

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Paul Smith
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Those windmill thingies look like a better bet. The small ones at windsave produce about a Kw. They also supply a doodad to put all electricity that is in excess of what you use back in the grid so it doesn't get wasted.

Solar panels are incredibly expensive and only seem to have about a 15 year lifespan. Unless electricity does become hugely expensive (it will probably double within a couple of years I think) solar panels just aren't worth the bother. If you have a south facing house then I think you'd be better off making green houses to grow fruit & veg that need a hot climate.

I visited an art gallery in France, which used photo-voltaic cells on the roof, AND a heat exchanger which passed water through pipes on the roof. The water temp could be guaged by putting your hand under a tap inside - it was pretty warm, even allowing it was raining on the day we were there! As for the electric cells, France has an advantage in it's climate, but coupled with energy conservation measures, the whole place slashed it's energy bills by 70%!!

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